Conventionally, vacuum cleaning apparatus disclosed in, for instance, Patent Document 1 is known. According to the vacuum cleaning apparatus, first, a depressurizing process of depressurizing a vapor cleaning and drying chamber into which a workpiece is loaded using a vacuum pump is performed. Afterwards, a vapor cleaning process of feeding vapor of a petroleum-based solvent to the vapor cleaning and drying chamber to clean the workpiece is performed. Next, an immersing and cleaning process of immersing the workpiece in the petroleum-based solvent stored in an immersion chamber and cleaning gaps in the workpiece which were particularly insufficiently cleaned in the vapor cleaning process is performed.
When the cleaning of the workpiece is completed in this way, the workpiece is transferred to the vapor cleaning and drying chamber again. Afterwards, a drying process of further depressurizing the vapor cleaning and drying chamber to evaporate the solvent adhered to a surface of the workpiece is performed. Then, when the drying process is completed, the vapor cleaning and drying chamber is restored to atmospheric pressure. Afterwards, the workpiece is unloaded, thus completing a series of processes.